In Reply.—We read with interest the letter substantiating our finding that subchronic treatment of normal subjects with lithium is associated with enhanced release of NE. We demonstrated that 2 weeks' (but not 1 week's) lithium administration significantly increased levels of urinary NE, NMN, and a derived measure of NE release ([NE +NMN]/ [NE+NMN+VMA + MHPG], in which VMA indicates vanillylmandelic acid, and MHPG, 3-methoxy-4-hydroxyphenylglycol). Interestingly, lithium produced a nearsignificant 20% increase in levels of NE in plasma but did not affect levels of MHPG in plasma.In their study of seven healthy volunteers, Poirier-Littre et al observe that 3-week treatment with lithium results in significant increases in levels of total DOPEG (66%) and sulfate-conjugated DOPEG (71%) in plasma. These findings are of considerable interest because Goldstein et al1 have recently demonstrated that DOPEG in plasma (DHPG) is derived primarily from sympathetic nerves and that procedures activating the sympathetic nervous system (eg,